Alternating drive, primarily for bicycles and similar driven vehicles

A reciprocating drive for a bicycle and or a similar driven vehicle comprising a frame and a driven wheel said driven wheel being rotatably mounted on the frame, said drive comprising a pair of cooperating drive units with complementary driving functions, each of said cooperating drive units being mounted to respective sides of the frame, said drive units each comprising a respective swinging arm pivoted on a respective shaft mounted to the frame to support its respective swinging arm for angularly reciprocating motion around its respective shaft, each swinging arm comprising a respective driving arm with a surface defining a driving path surface, said cooperating drive units comprising a common driving shaft mounted on said frame and rotatably mounted on said frame for rotating motion around a respective driving axis, each of said drive units comprising a respective axle with an axis substantially parallel to said driving axis and connected to and rotating on said common driving shaft along respective circular paths around said driving axis, and a driving follower connected to and pivoted on said bolt, said driving followers being biased to the associated one of said driving path surfaces so that movement of said driving followers moving in a first and then in a returning second direction along said associated driving path surface causing said swinging arm to perform an alternating swinging motion, said driving followers being mechanically coupled to each other through said common driving shaft and extend in substantially opposing directions from the axis of rotation of said common driving shaft, respective flexible ropes being connected to an associated one of said swinging arms, and respective biased rope drums mounted around the shaft of said driven wheel and connected to the driven wheel in a manner that allows transmission of torque to said wheel from said rope drum in a single angular direction of rotation, wherein said ropes are connected to and wound with respective predetermined number of turns around the associated rope drum so that during the driving operation the number of said turns is changing in a mutually alternating manner, each swinging arm further comprising a head portion surrounding its respective swinging shaft and connected to (i) an inner end of said driving arm;

• (ii) a traction arm, said traction arm having an inner end, said traction arm inner end being connected to said head portion, said traction arm and said driving arm each having respective outer ends opposite their respective inner ends;
• and (iii) a connection arm interconnecting the outer ends of said driving arm and of said traction arm, wherein said driving arm, traction arm and connection arm define together an opening, and the respective follower being positioned in said opening, said traction arm defining a traction support surface along its length that determines substantially the momentary transmission ratio, and each drive unit comprises at least one rope pulley so that said rope is connected to its respective arm by being wound around said rope pulley, said rope pulley comprising a shaft positioned on said traction support surface.